Starter motors

ABSTRACT

A starter motor including an electric motor driving a shaft. The shaft carries a pinion assembly, the pinion assembly being rotatable with the shaft and being movable axially along the shaft between a rest position and an operative position. An electromagnetic arrangment is provided for moving the pinion assembly from its rest position to its operative position and in the drive connection between the electromagnet arrangement and the pinion assembly there is a member which bears against one end of the pinion assembly, and which in the rest position of the pinion assembly is trapped between the pinion assembly and a collar carried by the shaft. The electromagnet of the electromagnet arrangement, when energised, moves the armature in such a manner that the pinion assembly is urged by way of said member towards its operative position. The shaft and the pinion assembly rotate relative to the armature and said member when the electric motor is energised, but the armature and said member act as a brake to rotation of the pinion assembly and the shaft when the pinion assembly returns to its rest position where the member is trapped between the pinion assembly and the collar carried by the shaft.

United States Patent mi Hollyoak 5] Nov. 25, 1975 i l STARTER MOTORS John David Hollyoak, Birmingham, England [75] Inventor:

[73] Assignee: The Lucas Electrical Company Limited, Birmingham, England [22] Filed: Oct. 3, 1974 [21] Appl. No; 511,501

Primary Examiner-James R. Scott Assistant Examiner-J. W. Redman Attorney, Agent, or Firm-Andrus, Sceales, Starke & Sawall [57] ABSTRACT A starter motor including an electric motor driving a shaft. The shaft carries a pinion assembly, the pinion assembly being rotatable with the shaft and being movable axially along the shaft between a rest position and an operative position, An electromagnetic arrangment is provided for moving the pinion assembly from its rest position to its operative position and in the drive connection between the electromagnet arrangement and the pinion assembly there is a member which bears against one end of the pinion assembly, and which in the rest position of the pinion assembly is trapped between the pinion assembly and a collar carried by the shaft. The electromagnet of the electromagnet arrangement, when energised, moves the armature in such a manner that the pinion assembly is urged by way of said member towards its operative position. The shaft and the pinion assembly rotate relative to the armature and said member when the electric motor is energised, but the armature and said member act as a brake to rotation of the pinion assembly and the shaft when the pinion assembly returns to its rest position where the member is trapped between the pinion assembly and the collar carried by the shaft.

8 Claims, 2 Drawing Figures 50 El I7 28 I3 28 Z7 24 E5 US. Patent Nov. 25, 1975 Sheet 1 of2 3,922,558

28 I3 28 E7 24 E5 FIGI.

US. Patent Nov. 25, 1975 Sheet 2 of2 3,922,558

FIGZ.

STARTER MOTORS This invention relates to starter motors for internal combustion engines.

A starter motor according to the invention includes an electric motor, a shaft rotated in use by said electric motor, a pinion assembly rotatable with said shaft and movable axially relative thereto between a rest position and an operative position, means for moving the pinion assembly from its rest position to its operative position, said means including a member which bears against one end of the pinion assembly and which in the rest position of the pinion assembly is trapped between the pinion assembly and a part carried by said shaft, and said means further including an electromagnet having an associated armature coupled to said member, the electromagnet when energised moving said armature so as to urge the pinion assembly, by way of said member, towards its operative position, the arrangement being such that when the electric motor is energised said shaft and said pinion assembly rotate relative to the armature and said member, and said armature and said member act as a brake to rotation of the pinion assembly and said shaft upon return of the pinion assembly to its rest position.

Conveniently said armature is generally concentric with said pinion assembly and said electromagnet is spaced in the direction of the shaft axis from said armature in the pinion assembly rest position.

Desirably the armature and said member can rotate with the shaft and pinion assembly and the inertia of said armature and said member provides the braking action when said member is gripped between the pinion assembly and said part upon return of the pinion assembly to its rest position.

Preferably the armature is guided for axial movement between a rest position and an operative position corresponding to the rest and operative positions of the pinion assembly, and the friction in the means guiding the armature aids the inertia of the armature and said member in providing the braking action.

Desirably the armature is guided by the poles of the electromagnet, a non-magnetic member being carried by the armature or the poles and being slidably engaged with the poles or the armature.

Alternatively the armature and said member are prevented from rotation with said pinion assembly and shaft, and the means preventing rotation accepts the braking forces as said member is gripped between said part and the pinion assembly.

Alternatively the electromagnet and its associated armature are arranged with their axis of operation parallel to and spaced from the shaft axis, and said mem her is coupled to said armature by way of a pivoted lever, said member being held against rotation with the shaft and the pinion assembly, the means holding said member against rotation accepting the braking forces.

In the accompanying drawings:

FIG. 1 is a sectional view of part of a starter motor in accordance with one example of the invention, the section being taken on a pair of planes which intersect at right angles on the axis of the starter motor, and

FIG. 2 is a sectional view of a starter motor in accordance with a second example of the invention.

Referring first to FIG. 1 of the drawings, the starter motor includes a hollow casing 11 including at one end an end bracket 12. Journalled for rotation within the casing 11 is a shaft 13 the shaft 13 carrying within the casing 11 the rotor assembly 14 of an electric motor. The stator assembly of the electric motor is carried by the casing 11, and the motor is generally conventional in that when energised it rotates the shaft 13. The shaft 13 projects from the rotor assembly 14, and terminates within a bearing 15 in the end bracket 12. Adjacent the rotor assembly 14, and rotatable with the shaft 13 is an abutment collar 16, and movable axially relative to the shaft 13 along the portion of the shaft intermediate the bearing 15 and the collar 16 is a generally conventional pinion assembly 17.

The pinion assembly 17 includes a carrier 18 coupled to the shaft 13 by way of axially extending splines l9 whereby the carrier 18 can move axially relative to the shaft 13, but can still be driven by the shaft 13 when the shaft 13 rotates. At its end adjacent the bearing 15 the carrier 18 is enlarged to define the outer component of a roller clutch assembly 21 the inner component of which is defined by a part integral with a pinion gear wheel 22.

The pinion assembly 17 can move relative to the shaft I3 axially between a rest position (as shown) and an operative position wherein the free end of the pinion gear wheel 22 abuts a stop member 23 on the shaft 13 adjacent the bearing 15. The pinion assembly 17 is urged towards its rest position by a pinion return spring 29 acting at one end against an internal cover member 30.

In order to move the pinion assembly from its rest position to its operative position there is provided an electromagnet arrangement including a pair of electromagnet poles (one of which is shown at 24) secured to the inner surface of the casing. Encircling each of the poles 24 is a winding 25 and associated with the poles is an annular armature 26. The armature 26 is concentric with the pinion assembly 17 and the shaft 13, and is mounted for axial movement relative to the shaft and pinion assembly by way of a brass sleeve 27 secured to the outer surface of the armature 26, and in sliding engagement with the inwardly presented faces of the poles 24. It will be appreciated that upon energisation of the windings 25 the armature 26 will be attracted towards the poles.

Secured to the armature 26 is an annular plate 28 which encircles the shaft 13, and which engages the end of the carrier 18 remote from the pinion gear wheel 22. In the rest position of the pinion assembly 17 the plate 28 is trapped between the pinion assembly 17 and the collar I6, the plate 28 being gripped between the pinion assembly and the collar by virtue of the action of the pinion assembly return spring 29.

The operation of the assembly is as follows.

Assuming the motor to be de-energised, and the components to be in their rest position then in order to start the engine associated with the starter motor the windings 25 are initially energised, and at this time of course the armature is in a rest position spaced axially from the poles 24. The attraction of the poles 24 upon energisation of the windings 25 causes the armature 26 to move towards the poles, and the connection between the armature 26 and the pinion assembly 17 by virtue of the plate 28, causes the pinion assembly to be moved axially relative to the shaft 13 towards its operative position. A short time after energisation of the windings 25 the electric motor of the starter motor is energised, and the shaft [3 and therefore the pinion assembly 17 start to rotate. The delay between energisation of the windings 25 and encrgisation of the electric motor can be achic\ ed in any com cnicnt manner, and the delay is chosen to permit the pinion a sembly to reach its operatne position vthercin the gear wheel 22 engages the toothed wheel of the engine. prior to energisation of the electric motor. Assuming that the pinion gear wheel 22 has moved fully into engagement with the toothed wheel olthe engine. then upon energisation of the electric motor of the starter motor the engine will be cranked. When the engine fires the electric motor and the windings 25 will be de-energised for example by the driver releasing the start switch of the vehicle. At this time. the return spring 29 will move the pinion assem bly and the armature back to their rest positions. Owing to the inertia of the rotor assembly 14 and the pinion assembly 17 the shaft 13. the rotor assembly 14 and the pinion assembly 17 will still be rotating when they reach their rest position. However, the armature 26 and the plate 28 will not be rotating, and so when the pinion assembly reaches its rest position and the plate 28 is gripped between the pinion assembly and the collar 16 then the inertia of the armature assembly will be added to the rotating mass, and will act as a brake rapidly stopping the rotation of the shaft 13 rotor assembly 14 and pinion assembly 17. In addition to the inertia of the armature 26 and plate 28 friction between the sleeve 27 and the poles 24 aids the braking action.

It will be appreciated. that during movement of the pinion assembly from its rest position to its operative position should a tooth to tooth abutment occur between the gear wheel 22 and the toothed wheel of the engine then the electric motor of the starter motor will still be energised after the predetermined delay. and the pinion gear wheel 22 will of course start to rotate disrupting the tooth to tooth abutment condition, and permitting the armature to move the pinion assembly into full engagement.

In a modification the armature 26 is physically held against rotation relative to the casing 11 of the starter motor. In this modification therefore the means physically preventing rotation of the armature accepts the braking forces when the pinion assembly returns to its rest position.

It is to be appreciated that the poles 24 ofthe electromagnet are magnetically interconnected by a circumferentially extending part of the casing 11. Thus the flux path of the electromagnet is from one of the poles. axially across the air gap between the pole and the armature. laterally within the armature. axially back across the air gap between the armature and the other pole. and from said other pole back to the first mentioned pole by way of the circumferentially extending part ofthe casing 11. Moreover. there may if desired be more than two electromagnet poles.

Referring now to FIG. 2, there is shown a starter motor wherein the electromagnet arrangement which moves the pinion assembly to its operative position is external of the main casing of the starter motor. The electromagnet arrangement is carried by the main casing of the starter motor. and has its operative axis parallel to and spaced from the axis of the shaft 13. Parts of the arrangement common to the starter motor described with reference to FIG. 1 have been indicated by the reference numerals they bear in FIG. 1.

The electromagnet arrangement includes an armature 41 movable on an axis parallel to but spaced from the a\is of the shaft 13. Movement of the armature 41 is transmitted to the pinion assembly byway of a lever 42 pivotally mounted on the casing 11 for movement about an axis 43. At its end remote from the armature 41 the lever 42 is bifurcated. the arms of the lever 42 extending on opposite sides of the carrier 18 of the pinion assembly 17 and being pivotally connected to an annular plate 44 equivalent to the plate 28 of the arrangement described with reference to FIG. 1. The pivotal connection between the lever 42 and the plate 44 of course prevents rotation ofthe plate 44 with the pinion assembly 17 and the shaft 13.

The electromagnet associated with the armature 4] is not shown in the drawing. but is of known form, and when energised, urges the armature 41 to the left so pivoting the lever 42 counter clockwise. and pushing the pinion assembly 17, by way of plate 44. to the right against the action of the spring 29. Upon dc-cnergisation of the electromagnet the pinion assembly is returned to its rest position by the spring 29, the armature 41 being returned to its rest position by way of the lever 42, and if desired by way of an additional return spring acting on the armature 41.

Operation of the arrangement shown in FIG. 2 is extremely similar to that described above, both during normal operation. and operation in a tooth-to-tooth abutment condition. When the starter motor and the electromagnet are de-cnergised and the pinion assembly 17, still rotating, reaches its rest position, the plate 44 will be gripped between the pinion assembly carrier 18 and the collar 16 and since the plate 44 cannot rotate there will be a braking action rapidly stopping the rotation of the shaft 13, the rotor assembly 14, and the pinion assembly 17. The braking forces are accepted by the arms of the lever 42 to which the plate 48 is pivotally connected. It will be understood that the pivotal connection between the plate 44 and the lever 42 per mits the plate 44 to remain at right angles to the shaft 13 even though the orientation of the lever 42 with respect to the shaft 13 changes as the armature 41 moves through its operating stroke.

In order to minimise the possiblity ofa tooth to tooth abutment condition occurring between the pinion gear wheel 22 and the toothed wheel of the engine in the above arrangements. and also to aid the spring 29 in re turning the pinion assembly to its rest position the connection between the pinion assembly carrier 18 and the shaft 13 may be by way of a helically splined coupling rather than the axial splines described above. In such an arrangement. during the movement of the pinion assembly from its rest position to its operative position the pinion assembly is rotated relative to the shaft 13 as well as moving axially relative to the shaft. Moreover, upon de-energisation of the electric motor the pinion assembly which is coupled to the toothed wheel of the engine will tend to rotate faster than the shaft 13, and the helically splined connection will aid the spring 29 in withdrawing the pinion assembly back to its rest positionv The roller clutch 2] of course prevents the electric motor being driven by the toothed wheel of the engine should a fault cause the pinion gear wheel 22 to remain engaged with the toothed wheel of the engine when the engine is runningv I claim:

I. A starter motor for an internal combustion engine including an electric motor. a shaft rotated in use by said electric motor, a pinion assembly rotatable with said shaft and moveable axially relative thereto between a rest position and an operative position, means for moving the pinion assembly from its rest position to its operative position. said means including a member which bears against one end of the pinion assembly and which in the rest position of the pinion assembly is trapped between the pinion assembly and a part carried by said shaft, and said means further including an electromagnet having an associated armature coupled to said member, the electromagnet when energised moving said armature so as to urge the pinion assembly, by way of said member towards its operative position. the arrangement being such that when the electric motor is energised said shaft and said pinion assembly rotate relative to the armature and said member, and said armature and said member act as a brake to rotation of the pinion assembly and said shaft upon return of the pinion assembly to its rest position.

2. A starter motor as claimed in claim I wherein said armature is generally concentric with said pinion assembly and said electromagnet is spaced in the direction of the shaft axis from said armature in the pinion assembly rest position.

3. A starter motor as claimed in claim 1 wherein the armature and said member can rotate with the shaft and the pinion assembly and the inertia of said armature and said member provides the braking action when said member is gripped between the pinion assembly and said part upon return of the pinion assembly to its rest position.

4. A starter motor as claimed in claim 3 wherein the armature is guided for axial movement between a rest position and an operative position corresponding to the rest and operative positions of the pinion assembly, and the friction in the means guiding the armature aids the inertia of the armature and said member in providing the braking action.

5. A starter motor as claimed in claim 4 wherein the armature is guided by the poles of the electromagnet. a non-magnetic member being carried by the armature or the poles and being slidably engaged with the poles or the armature.

6. A starter motor as claimed in claim 1 wherein the armature and said member are prevented from rotation with said pinion assembly and shaft, and the means preventing rotation accepts the braking force as said member is gripped between said part and the pinion assem- My 7. A starter motor as claimed in claim 1 wherein the electromagnet and its associated armature are arranged with their axis of operation parallel to and spaced from the shaft axis, and said member is coupled to said armature by way ofa pivoted lever, said member being held against rotation with the shaft and the pinion assembly. the means holding said member against rotation accepting the braking forces.

8. A starter motor as claimed in claim 7 wherein said means holding said member is said lever. 

1. A starter motor for an internal combustion engine including an electric motor, a shaft rotated in use by said electric motor, a pinion assembly rotatable with said shaft and moveable axially relative thereto between a rest position and an operative position, means for moving the pinion assembly from its rest position to its operative position, said means including a member which bears against one end of the pinion assembly and which in the rest position of the pinion assembly is trapped between the pinion assembly and a part carried by said shaft, and said means further including an electromagnet having an associated armature couPled to said member, the electromagnet when energised moving said armature so as to urge the pinion assembly, by way of said member, towards its operative position, the arrangement being such that when the electric motor is energised said shaft and said pinion assembly rotate relative to the armature and said member, and said armature and said member act as a brake to rotation of the pinion assembly and said shaft upon return of the pinion assembly to its rest position.
 2. A starter motor as claimed in claim 1 wherein said armature is generally concentric with said pinion assembly and said electromagnet is spaced in the direction of the shaft axis from said armature in the pinion assembly rest position.
 3. A starter motor as claimed in claim 1 wherein the armature and said member can rotate with the shaft and the pinion assembly and the inertia of said armature and said member provides the braking action when said member is gripped between the pinion assembly and said part upon return of the pinion assembly to its rest position.
 4. A starter motor as claimed in claim 3 wherein the armature is guided for axial movement between a rest position and an operative position corresponding to the rest and operative positions of the pinion assembly, and the friction in the means guiding the armature aids the inertia of the armature and said member in providing the braking action.
 5. A starter motor as claimed in claim 4 wherein the armature is guided by the poles of the electromagnet, a non-magnetic member being carried by the armature or the poles and being slidably engaged with the poles or the armature.
 6. A starter motor as claimed in claim 1 wherein the armature and said member are prevented from rotation with said pinion assembly and shaft, and the means preventing rotation accepts the braking force as said member is gripped between said part and the pinion assembly.
 7. A starter motor as claimed in claim 1 wherein the electromagnet and its associated armature are arranged with their axis of operation parallel to and spaced from the shaft axis, and said member is coupled to said armature by way of a pivoted lever, said member being held against rotation with the shaft and the pinion assembly, the means holding said member against rotation accepting the braking forces.
 8. A starter motor as claimed in claim 7 wherein said means holding said member is said lever. 